The present invention relates, in general, to watthour meters and meter sockets and, more specifically, to watthour socket adapters or extender adapters for mounting, recording and other instrumentation equipment on ringless style watthour meter sockets.
In the electric utility industry, plug-in, socket-type watthour meters are commonly employed to measure electric power consumption at a residential or commercial building establishment. A socket is mounted on a wall of the residence or building and contains terminals which are connected to electric line and electric load conductors. The terminals are also connected to internal conductors within the socket which extend to jaw contacts positioned to receive the blade terminals of a plug-on watthour meter to complete an electric circuit through the watthour meter between the line and load terminals and the conductors.
One type of meter socket has a ring-type cover which includes an outwardly projecting, annular mounting flange surrounding an opening in the cover through which the blade terminals of a watthour meter extend. The mounting flange is sized to mate with a complementary formed mounting flange on the base of the watthour meter. The two mating mounting flanges are held together by a sealing ring.
Another type of meter socket has a ringless style cover which has only a slightly raised boss surrounding an aperture in the cover. The meter and/or socket adapter is connected to the jaw contacts in the socket and has an end portion which extends through the aperture.
While a socket adapter can be easily attached to either meter socket cover style for receving a plug-in watthour meter, it is necessary sometimes to connect load survey equipment or recording equipment to the meter socket for various study and reporting surveys. Since such equipment is frequently contained in a housing which is too large to pass through the aperture in the socket cover or to be connected to the mounting flange in a ring style cover for connection to the socket jaw contacts, latch base socket adapters have been devises which include the standard jaw blades for receiving blade terminals in the survey equipment in a plug-in connection, with ends of the jaw blades passing through the latch base for plug-in connection to the socket jaw contacts. Such a latch base includes lock members which are engagable exteriorly of the socket cover to move latch fingers behind the latch cover to securely mount the latch base to the socket cover on a meter socket.
One prior art approach to providing a latch base socket extender adapter is shown in FIGS. 1A and 1B. This extender adapter is modeled after Ekstrom Industries, Inc., 38 series extender adapter and is formed of a two-part base and shell. The base, shown in FIG. 1A, has a circular cross section formed of a bottom wall, a radially outward extending mounting flange and a short length side wall. A plurality of apertures extend through raised bosses on the base wall and the base wall for receiving the blade end of jaw blades shown in FIG. 1B mounted through the shell and base for interconnection with the socket jaw contacts.
A plurality of mounting screw bosses are disposed internally of an annular ring concentric within the mounting flange and extending from the base wall. The bosses receive mounting screws to which an L-shaped, steel latch flange is attached. The bosses guide movement of the L-shaped latch flange as the screws are threaded in and out relative to the base. Such movement of the screws bidirectionally extends a lower leg of the latch flange mounted around each screw underneath the adjoining raised boss on the ringless socket cover to fixedly attach the base to the metal surrounding the opening in the cover. Since the heads of the screws are disposed externally of the side wall of the base as part of a cast metal ring mounted around the side wall of the base on one side of the mounting flange, the base end of the extender adapter can be mounted through the opening in the ringless socket cover after the cover has been installed on the meter socket.
Bore are cross drilled in the screw heads for receiving a meter seal which extends through an adjacent aperture in an ear formed on the metal ring after the screws have been threaded to their fully latched position.
The shell has a bottom wall and a side wall extending therefrom to an external mounting flange mateable with complimentary mounting flanges on load survey recording equipment or other metering instrumentation. Bosses in the shell support the jaw blades which pass through the bottom wall of the shell and the bottom wall of the base for connection at a blade end with the socket jaw contacts. The shell is fixedly attached to the base by screws which extend through apertures in the bottom wall of the shell into bores formed in mounting bosses in the base as shown in FIGS. 1A and 1B.
While such an extender adapter proves an effective means to install load survey recorders and other types of meter recording equipment or instrumentation on ringless style sockets, it is difficult to reliably seal the shell to the base which can lead to corrosion. Further, as shown in FIG. 1A, the interior ends of the screws are disposed in close proximity to the jaw blades extending between the bottom wall of the shell and the bottom wall of the base. This creates an arcing potential. Further, there is no capability for accommodating a watthour meter having an external accessory box or an external wire which needs to be routed through the socket adapter into the meter socket.
A different approach to a latch base type socket adapter is one sold by Marwell Corporation as Model No. E/Z 1800. In this socket extender adapter, the cast ring and screw head seal ears are integrally molded as part of the short side wall of the base which has a double thickness compared to the latch base socket extender adapter shown in FIGS. 1A and 1B. The inside pocket surrounding the inner end of each screw has one higher length wall at a radially inner end. However, the other two side walls remain short exposing the metal screw and the latch flange to arcing potential from adjacent jaw blades.
This design also presents difficulties inadequately sealing the shell to the base which can lead to corrosion. Further, the close proximity of the screw seal ears and the screw heads prevents the use of the popular Plastic Padlock Seal sold by E.J. Brooks Company, Livingston, N.J.
In both latch base adapters shown in FIGS. 1A, 1B and 2, the mounting screws are retained in the base by means of roll pins inserted through holes drilled in the enlarged bosses on the ring and into an annular recess formed in each screw. Such roll pin captures a screw relative to the ring while allowing the screw to rotate to move the attached latch member between the latched and unlatched positions. However, the drilling of the holes in the ring for each roll pin and the mounting of the roll pins in the holes requires additional assembly steps and time which increase the cost of these prior latch base adapters.
Another deficiency of the prior art latch base adapters shown in FIGS. 1A, 1B and 2 is that only, wire tamper indicating seals can be mounted through the screw heads and the ears for flanges on the ring to indicate that screws are in their final, latch engaged position without tampering or attempts to remove the latch base from the socket cover.
Thus, it would be desirable to provide a latch base watthour meter socket extender adapter which overcomes the problems associated with previously devised latch base socket extender adapters. It would also be desirable to provide a latch base socket extender adapter which has the mounting ring, base wall screws and latches formed as a one-piece assembly, which can accommodate different diameter shells so as to eliminate the need for a shell to base seal, which fully encapsulates the interior end of the mounting screws for high arc resistance, which accommodates seals for the mounting screws, which can easily accommodate a conventional watthour meter sealing ring, which has a frangible mounting flange to adapt to ring style socket covers with varying opening mounting rings, which has gas vent and external wire passage, strain relief apertures and, finally, or which has optional top and bottom swing latches to provide an internal mounting connection to a meter socket cover. It would also be desirable to provide a latch base socket extender adapter which can receive a meter sealing ring which encompasses the drive member or screw heads to prevent any unauthorized access to the mounting screws in an attempt to unauthorizedly remove the latch base from the socket cover. It would also be desirable to provide a latch base socket extender adapter which has a reduced manufacturing cost as compared to prior art latch base adapters by eliminating the need for the prior art use of roll pins and holes in the ring.
Watthour meter socket adapters in general which are formed of a base and a shell, either integrally formed or separately attachable and which are mountable in a watthour meter socket through an aperture in a ringless style meter socket cover or to a mounting flange on a ring style cover have some of the same deficiencies noted above for latch base adapters.
It is difficult to easily pass flexible conductors or wires from the watthour meter though the adapter to equipment mounted in the meter socket. In addition, it is still necessary to accommodate a sealed fit between the separate base and shell. Further, ring style socket adapters and ringless style socket adapter still require two different adapters.
Thus, it would be desirable to provide a watthour meter socket adapter which overcomes these deficiencies.
The present invention is watthour meter socket adapter. In one aspect of the invention, the socket adapter has a latch base which is mountable through the aperture in a meter socket cover to enable metering devices, such as load survey recorders, etc., to be temporarily connected to the jaw contacts in the meter socket.
The inventive latch base adapter includes a housing having a base with the flange extending radially outward from the base. An annular ring extends from the base and the flange and carries a mounting flange at an outer end. A plurality of drive members, such as screw fasteners, are radially extendable thorough the ring. A latch is coupled to each drive member for movement into engagement with the meter socket cover adjacent to an aperture in the cover.
In one aspect of the invention, conformable means in the form of at least one annular discontinuity, is carried on the annular ring for adjusting the engagement of the ring with a shell attachable to the housing. In another aspect, trap members are carried in the housing for axially capturing the drive members to enable the drive members to rotate without axial movement relative to the annular ring. The trap members include a wall extending from the housing and having at least one edge angled with respect to the longitudinal axis of the drive member. The edge of the wall cooperates with a recess carried on each drive member to prevent axial displacement of the drive member during rotation of the drive member.
In another aspect of the invention, each latch member has at least one projection which engages the ring on full outward positioning of the latch and causes a lever action to be exerted on the latch member to drive the other leg of the latch member into tight engagement with the cover to mount the latch base of the adapter to the socket cover.
In another aspect of the invention, at least one seal member is carried on each drive member for environmentally sealing each drive member to the annular ring. The seal member may be mounted in an annular recess carried on each drive member.
In another aspect of the invention, the flange extending from the base of the housing includes frangible means for enabling an outer ring portion of the flange to be separated from the remainder of the flange to conform a single latch base design for use on both ring style and ringless style meter socket covers.
In another aspect of the invention, barrier means are carried in the housing for electrically insulating each drive member from adjacent electrically conductive elements in the housing. The barrier means encompass substantially all sides of the drive member projecting interiorly of the annular ring. The barrier means may be combined with the trap members so that the trap members are carried on the barrier means to provide both axial capturing and insulating features.
In another aspect of the invention, at least one flange is carried on and extends radially outward from the annular ring on the housing. An aperture is formed in the flange and is alignable with an aperture formed in the head portion of the drive member exteriorly of the annular ring. A seal indicator, such as a wire lead seal or meter padlock seal is extendable thought the aligned apertures to indicate a sealed position of the drive member. In another aspect, one edge of the flange is spaced from the flange in the housing and defines a recess for receiving one portion of a sealing ring mountable about the flange and the drive member.
In another aspect of the invention, a plurality of ribs are formed on the annular ring. The ribs have a tapering outer edge to center the shell with respect to the housing. This eliminates the need for a silicone seal used in the prior art to seal the shell to the base.
In another aspect of the invention, at least one and preferably a plurality of apertures are formed through the base of the housing. A plurality of resilient fingers are formed in the base and extend from the aperture. Each finger has a free end located at the aperture to form a strain relief for an electrical conductor passing through the aperture into the meter socket. The apex edge of the free end of each finger is bendable from the plane of the base to lockingly engage the conductor extending through the aperture and to prevent the conductor from easy withdrawal through the aperture.
In another aspect of the invention, a plurality of latch members are carried on the base of the housing and movable between a first retracted position allowing insertion of the housing through an aperture in a socket cover, and a second extended position to fixedly latch the housing to the cover. The fastener is extendable through the housing and one latch member. The latch member is mounted on the fastener so as to be rotatable with the fastener. In one aspect, the fastener is the same fastener used to mount the shell to the mounting flange of the housing.
The electrical power service apparatus in the form of a meter socket adapter with a latch base overcomes many of the difficulties encountered with previous watthour meter socket adapter latch base designs.
The conformable wall of the annular ring allows the ring on the base to accommodate different diameter shells for easy manufacturing and versatility in application of the inventive latch base.
In another aspect, the barrier means completely electrically insulates the conductive portions of the latch drive members, typically the screw fasteners, from adjacent electrically conductive jaw contacts or jaw blades in the housing to provide a high arc resistance.
The unique provision of openings in the latch base with resilient edges provides strain relief for the passage of conductors through the latch base to the meter socket.
The arrangement of the drive member head and the adjacent flange on the annular ring formed as one piece with the latch base enables the use of the inventive latch base with both ring style and ringless style meter socket covers. In addition, conventional watthour meter socket sealing rings may be uniquely mounted over the head and the flanges of each latch drive members to encompass the latch drive members in the latch engagement position and prevent access to the drive members during an unauthorized attempt to remove the latch base from the socket cover.
In another aspect of the invention, the base wall mounting end is conformable in diameter to mate with different diameter shells so as to eliminate the need for a separate, low reliability, silicone shell to base environmental seal.
In another aspect, the ear or flanges on the base ring and the slots through the latch drive member heads are configured to accommodate any conventional meter seal device, such as a plastic pad lock seal or wire lead seal.
In another aspect, optional latch members used by themselves or in combination with the aforementioned latch drive members are mountable on the rear outer surface of the latch base and are pivotal between latching and unlatching positions to releasably affix the latch base to a meter socket cover. Preferably, the fasteners used to attach the shell to the base extend through the base and are engagable with the latch members for moving the latch members between the latched and unlatched positions.
In another aspect of the invention, the socket adapter includes a base and a shell which are joined together by fasteners. The conformable means described above carried on the annular ring of the base for adjustably accommodating the sealed engagement of the base with the shell can be advantageously employed for many other watthour meter socket adapters, not just latch base socket adapters.
In another aspect, the frangible rim described above may also be employed in other types of watthour meter socket adapters to enable an outer portion of the mounting flange to be separated from the remainder of the flange to conform the watthour meter socket adapter base for use on both ring style and ringless style meter socket covers.
In another aspect, at least one and preferably a plurality of apertures are formed in the base of the socket adapter. A plurality of resilient fingers are formed in the base and extend from each aperture. Each finger has a free end located at the aperture to form a strain relief for an electrical conductor passing through the aperture into the interior of the meter socket. The apex edge of the free end of each finger is bendable from the plane of the base to lockingly engage the conductor extending through the aperture to prevent the conductor from easy withdrawal from the aperture.
In yet another aspect, a plurality of latch members carried on one surface of the base, which are described above, may be employed for mounting a conventional watthour meter socket adapter base to a meter socket cover. The latch members are movable between a first retracted position allowing insertion of the socket adapter housing through an aperture in the socket cover to a second extended position to latch the socket adapter base to the socket cover. The fastener extendible through the shell and base of the housing to connect the shell and base together also receives one latch member to enable the latch member to be rotatable with rotation of the fastener.